Erythropoietin (EPO) is a glycoprotein hormone and hematopoietic factor, which is mainly produced in the human kidney. EPO promotes the production and release of red cells in bone marrow. In 1985, recombinant human erythropoietin (rhEPO) was synthesized by gene engineering. Due to its mitogenic and differentiation-promoting actions, rhEPO can bring about the effect of blood transfusion, while not putting patients on risk of viral infection or excessive transfusion. Hence, it has played an important role in treating renal anemia. Meanwhile, rhEPO is a novel stimulant in sports games due to its action of increasing oxygen carrying capacity and exercise tolerance. In 2005, rhEPO was listed by the International Olympic Committee (IOC) and World Anti-Doping Agency (WADA) as the first peptide substance banned in sports games.
EPO and rhEPO have the same biologic activities and very similar molecular structure, and their only difference lies in the isoelectric point. EPO has an isoelectric point of 3.7-4.7, and rhEPO has an isoelectric point of 4.4-5.1. Therefore, it is difficult to discriminate EPO from rhEPO. EPO and rhEPO discrimination has long been relying on the combination of mass spectrometry, isoelectric focusing and gel electrophoresis. Nevertheless, these detection methods have some drawbacks, such as long separation time, low detection efficiency, and poor specificity. Therefore, they are not fit for fast, accurate discrimination of EPO and rhEPO. It is imperative to develop a highly specific, sensitive, fast, and accurate method to discriminate EPO and rhEPO.